<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>字符串的表达式</title>
</head>
<body>
    <script>
        let str = "hello world";
        //是否包含"v"
        console.log(str.includes("v"));
        //以什么开始
        console.log(str.startsWith("h"));
        //字符串长度
        console.log(str.length);
        //字符串以什么结尾
        console.log(str.endsWith("d"))
    </script>
</body>
</html>